1. Field of the Invention
The present invention relates to wireless communications, and more specifically to a method and apparatus for providing optimal uplink data rates to mobile stations when mobile networks send parameters controlling the data rates.
2. Related Art
Mobile networks are often used to provide communication between mobile devices. In general, mobile networks contain systems such as base stations which communicate over air with individual mobile devices using 3G and IEEE802 cellular technologies such as CDMA20001xEV, UMTS/HSDPA/HSUPA, IEEE802.16e/WiMAX. Additional communication infrastructure is provided to facilitate communication between distant mobile devices.
An often important consideration in mobile environments based on digital communication technologies is the rate (amount of data per unit time) at which a mobile station can send data to the mobile network. The data rate is generally referred to as uplink data rate. In general, a higher uplink data rate implies that the mobile station can transmit correspondingly more data per unit time (in the allocated time slots) to the mobile network.
Uplink data rates are often controlled by parameters received from mobile networks. For example, in the CDMA 2000 environment, a base station sends parameters known as reverse activity bit (indicating whether the uplink rate can be increased or decreased), rate limit (maximum rate at which the mobile station can transmit), and transition probabilities (indicating the probability with which the data rate can be increased or decreased) etc., which are then used by each receiving mobile station to determine the corresponding uplink data rate. The manner in which the parameters control the uplink data rate is described in further detail in a standard document entitled, “CDMA 2000 high rate Packet data air interface specification”, available from Third Generation Partnership Project 2 (3GPP2).
There is a general need to provide optimal uplink data rate to mobile stations. Providing too high a data rate may be considered ‘unfair’ since the data rates of other mobile stations may be correspondingly reduced (to keep interference within manageable levels).
On the other hand, providing too small a data rate may lead to several disadvantages. For example, in situations in which several types of multi-media applications are supported in the mobile network and mobile stations, too low a bandwidth may impede the ability of mobile stations to provide desired quality of service (QoS) (e.g., low latency for voice or bursty/high transfers for data networks access applications) to different applications.
Accordingly, what is needed is a method and apparatus to provide optimal uplink data rate in environments such as those described above.
In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.